Every year around winter time people get worried about Vitamin D, they read it somewhere or hear others talk about it. So what is it all about? Symptoms of Vitamin D deficiency can be very subtle and that is why you should take this very serious. You might lack it and not know, better keep on reading and check for yourself.
Some „technical“ info about Vitamin D
Vitamin D functions as a hormone. There are two major forms:
– vitamin D2 – found in fungi, plants, fortified foods, supplements
– vitamin D3 – synthesized in our skin when exposed to UVB light, found in animals, fortified foods and supplements
Vitamin D regulates over 200 genes in our body, it activates genes by binding to vitamin D receptors of cells, it regulates calcium and phosphorus levels in the blood (important for bone growth and remodeling), acts as an immune modulator (to suppress the immune system and fight rheumatoid arthritis, lupus, and multiple sclerosis) and activates the immune system to fight cancer and infections.
The synthesis in our skin requires exposure to UVB light at certain wave lengths (270-300 nanometers). It gets processed in the liver (to 25-hydroxy vitamin D), then processed again in the kidney (to 1,25 dihydroxy vitamin D). The balance of UVA/UVB depends on time of day, early and late in the day there is only UVA around. More UVB is available close to solar noon. The balance changes with latitude, time of day, season of year (all reflected in UV index). Avoid skin exposure when UV index is less than 3.
Vitamin D is measured by levels of 25(OH)D(calcidiol). A normal level ranges from 20-70 ng/mL, a deficiency means calcidiol level
sun exposure – where and how long to get it
The best source to get Vitamin D is sunlight exposure when the UV index is 3 or greater. An adequate exposure means: 50-75% of skin is exposed, best time is between 10:30 AM and 2-3 PM, with a UV index of 3 or higher. After maximum UV exposure, additional vitamin D produced is degraded. Other sources: supplementation for vegans or foods like cod liver oil. The UV index is an international standard measurement of the strength of UV radiation from the sun. A prediction of UV intensity when the sun is highest (a 2-4 hour period surrounding solar noon). Its purpose is to help protect people from UV light.
In the table you can see the time you can spend depending on your skin type and the current UV index. On the iPhone weather app you can see the current UV index when you scroll all the way down to the bottom. Please note: if you are 50 or older you need double exposure time.
On another note: it might seem a little confusing that darker colored skin needs longer but as we also know dark-colored skinned people can stay longer in the sun so this makes sense with the Vitamin D consumption of different skin types.
Deficiency and toxicity
A Vitamin D deficiency can contribute to diseases and disorders like myalgias, cancer, diabetes, high blood pressure, congestive heart failure, impaired bone mineralization (leading to rickets), osteoporosis, autoimmune conditions (rheumatoid arthritis, multiple sclerosis, lupus), depression and seasonal affective disorder (SAD). Inadequate sunlight exposure stemming from geography, time in the sun, sunscreen can contribute to Vitamin D deficiency as well as diseases of liver and kidneys and obesity.
Dark skinned people, older people and obese people have a higher risk of developing a Vitamin D deficiency.
If you wonder if you can get vitamin D toxicity – Upper limit considered safe for a healthy adult: 250 micrograms or 10,000 IU/day. Overexposure to sunlight cannot cause toxicity; supplementation can. That’s why supplements should be administered under physician supervision.
UV light can damage cellular DNA (skin cancer risk). Some sun exposure may actually be protective against cancer. But burning is probably cancer-promoting, but no sun exposure seems to be too. Studies showed a healthy middle way might be the best solution. As a „healthy middle way“ recommendation get adequate sun exposure based on the UV index and skin type, then use a “barrier method” (sun block, shirts, hats, etc.).
In case you like tanning booths please note: they’re not all the same because they may use UVA, UVB, UVC light bulbs. Only bulbs that utilize UVB light have any potential benefit. The natural ratio of UVA:UVB light from the sun ranges from 10:1 to 20:12; tanning bulbs may go as high as 100:1 !!! You better ask in the tanning salon, if the person there does not know kindly ask to get that information, it is your body, your life, your health. An adequate (not excessive) sunlight exposure is best for safe accumulation of Vitamin D.
Vitamin D is essential for your health. A Vitamin D deficiency means a deficiency in sunlight exposure. Low levels of Vitamin D have been associated with multiple diseases.
The best way to get Vitamin D is from sunlight, get it whenever it is possible. Get advice from your doctor in case you would like to supplement or if you think you wont get enough sunlight. There are no studies yet showing raising levels with supplements will bring the same level of health as natural exposure.
Read more here: http://epa.gov/sunwise/uvindex.html
All of this is of course a summary edited for an easier understanding of a way more complex topic. More technical terms are always possible but way too confusing. In case you don’t understand something feel free to contact me in the comment section.